Ringless piston



April 12, 1938. o. c. PILLAR RINGLESS PISTON Filed Sept. 9, 1956 5 Sheets-Sheet 1 H 1|]. 0 A \O 7% 2% m INVENTOR asa/vx jflz 1. 17A

NEY

April 12, 1938. o. c. PILLAR Filed Sept 9, 1956 5 Sheets-Sheet s j! 9 Hi :1 J6 1, Wm 1 I .10 I /4 J .,1 J /5' I fl ATT RNEY Patented Apr. 12, 1938 ome STATE i amomss rrs'ron Oscar i -i1 o. Valleyylag Application momma, 1192s,.- smegma i T a The present invention relates to pistons" used in reciprocating engines andimoreparticularly inan-o 1 ll- -lloiwmg; 9;.- l"ig."11 represents asection on line li -Ito! Fig.1; "Fig;12 representra :per-

, toa piston in which the usual sealing rings are I the: invention prior to assembly with Ian associdispensed with. w This application 1 for patent is a continuation 'in' "part 01 application, Ser; No. :t:

' part tdbe assembled with the part shown in ;Fig."-12 to'iorm a-complete unitary seiin expand- In the of pistonsofthe typeato which this" i invention relates it has heretofore been considered impractical, it not'impossible, to' obtain "emcient results without'employing spring expan-r" 1 fsion rings'to maintain compression and prevent" leakage. "Such'ringshave always been'a source wof trouble due to failure to stand upunder "hard use, wear with incident leakage, scoring of cylin ders, and the like; Also'the costof rings and'l replacement charges add to the i disadvantages of;

e in two longitudinal sections" and which are z-iormed astwo separate segmental castings. designed toxbe'united toiorm anunitary substan- L Some of the objects of thepr'esent invention are to provide an improved piston for use in tspective of "onerpart of another modification of ated part; Fig.13 represents a perspective'of the in: piston; Fig. 14 represents a section-on line ilk-M of Fig-.12 with thepart norm," 13 in assembled positionwFim. 15 represents a section 10 on 1ine-ii-li-oi Fis.-12; 1'13; 16 represents a sectional elevation ot the assembled-piston; E and reciprocating engines; toprovide a novelvm'ethodw wherein piston rings have been eliminated; to provide aringless piston wherein: provision is I i made for proper lubrication of the relatively-II moving parts; to provide aringles's pistonwhe'rein friction inuse ,is'reduced toa minimum; to

of the section I i and provide aleakt-prooif" closure of making arin'gless-piston; 'toprovidea piston v *Iig. PT -"represents awperspeotive' of one of the fastening pins."-

. Referringitoi.ther drawingsone' iorm oi' i the present-invention consists .of a piston ll formed icular contour. and havingia diameter-suitable to fitsnugly within the cylinder in which the piston provide a novel joint in a self expanding piston;

d to provide a- 'one piece pist on having a' flxedpart and a movable part, thel'atter servingto main tain a leak proof joint between the walls 'ofthe piston and the" cylinder in which the piston is' usedpto provide a self-expanding 'pistonhaving wrist pin: bosses so arrangedrthat' the assembled wrist pin is not subjected tolateral-strains due to the action ofthe expanding element; and to appear.

provide other improvements as" will hereinafter In theaccompanyingdrawings Fig; 1 -'repre 'sents' a side eievationof a piston' embodyingone form of the presentinvention; Fig.2 represents 1 a side elevation 01 the parts or thepiston before r "assembly; Fi'g.3'representsa-transverse section "one part of a modiiiediorm'of the invention prior" head l3 projects laterally beyond the, two. edges isto: be used.pAs will be seen ;from Flg.. 2;the

or the sectionv in order torclose theupper end 25 for the upper end 0! both sections. The section l I "is shorter than "the section 12 by an amount suflicient to properly fitthehead liintoplace, 30

One edge I! o! the-section IZ is preferably a straight edge designed tOrflbllt alike edgeof; the section ilswith these two edgesin abutting -relation a step in the methodconsists inwelding the abutting partsetogetherin: a Joint-'28. 31 Pref erably at thewtime ot weldingttheinternalwall of the' pistcn bodyalong the Joint isbuilt; up as indicated at to provide a vsuitable reinforcement. This welding operation" serves also to give the required setting .for spring action.

-In'order-topermit. the desired springzexpansion 40 ot'the section II with airespect to; the section, I2,

"-the 'other two:opposed edges I! and ILOI the respective sections and 12 are not connected together but are complementaily cut so that slcnv gitudinally consider'edone part isvofiset with re- "spectto the remainingpart to form; an overlapto assembly withthe" associated parts; "Fig. 7 representsa-perspective ofthe part to beassembled with'the part shown in Fig; stororm a" completeunitarvseli expanding piston: Fig. 8

represents a bottom m une representsa 'section on line 8-! of Fig; 10; Fig. 10 *represents a' section on'line" ping joint.

.- That portion oftheaedges Hand l5 whichzmeetsthe head i3 isprovided withiopposedlengthwise grooves; l6 and H for therecep tionoi *a sealing tongue l8. in assembled *condition with the tongue Iii-"in place oil is pre- -'plan of the assembled piswIn order toreduce friction theworkinglend of ventedi'rom escaping alongthejoint.

each section is formednwith a 'lpluralitysoftiace grooves 2i so that the area of the bearing face of the piston is materially reduced without in any way lowering the efllcient working of the piston. Oil holes serve as return passages for any oil collecting in the grooves 2|. The skirt portion of the piston likewise has its outer face cut away by a circumferential groove to reduce friction.

Wrist pin bosses 25 are provided in the fixed wall of the assembled piston for the usual purpose of mounting the connecting rods, as will be understood.

In carrying out the method of forming the piston of the present invention, the two sections are cast'or otherwise shaped .to the required dimension and machined as necessary. The two sections are then placed with the two edges I! in abutting relation, while the opposite two edges are held apart by the interposition of a spacing block 21. In this position the section II is in its maximum expanded position with respect to the section It. The meeting edges ii are then welded together and the reinforcing rib 24 formed. This heating serves to set the sections so that the movable section II can expand relative to the fixed section II. The block 21 is now removed and the piston ready for assembly with associated parts.

In connection with the grooves II it should be noted that these stop short of the joint between the edges l4 and II so that each has a closed end to prevent leakage of oil. It will now be appar-- cut that a complete unitary piston structure has been devised wherein a sectional structure is formed into a one piece expansionable piston in which the use of piston rings has been entirely eliminated. Furthermore by the present construction increased compression is obtained and since the forces acting on the piston are always in the nature of a push the parts are at all times maintained in joint sealing position in so far as the head and the expansionable member are concerned. It should also be noted that the novel Joint sealing means formed-by the tongue and groove construction I and I8 will act to seal against oil leakage and the coagulation of oil on this tongue will gradually build up a solid joint closing barrier against loss of oil.

In the form of the invention shown in Figs. 6 to 11 inclusive the piston is made up, like the form heretofore described, of two separate and distinct parts welded or otherwise secured together so that one part is capable of movement relative to the other and this part is so arranged and constructed as to maintain a constant pressure in opposite directions from the axis of the wrist pin. Fig. 6 illustrates the part A forming in the assembled piston the fixed part relative to which the part B, shown in Fig.7, moves. As shown in Fig. 6 the part A consists of a cylindrical head formed integral with a'segmental depending side wall Ii having an arc length of approximately seventy degrees. The lower portion of the wall Ii is provided with an extension I! forming a true circle arc terminating at an arcuate distance C from the end of the wall 3|. This extension 32 therefore provides an arcuate space 3| between its upper margin and the head II to receive the expansible movable element as will be described. The wall 3| has a boss 34 integral therewith which is reinforced by a rib 35 extending upwardly along the face of the wall II and terminating as an integral part of the head 30. Diametrically opposite to the boss 34 is the other boss 36 for carrying the other end of the wrist pin,this boss 38 being cast or formed integral with the extension 32. A rib 31 extends from the boss 36 to the head 30 and has its ends respectively integral with these parts. It should be noted, however, that the rib 31 is spaced from the inner wall of the extension 32 to provide a clearance 38 so that the movable or expansible part (presently to be described) is free to move without contacting the aforesaid rib 31.

As shown in Fig. 7 the part B consists of a wall segment ll! having an arc length oi approximate 1y one hundred and six degrees which is integral with and depends from a segmental band I. This band ll is of a width to fit snugly in the arcuate space 33, and is of a length and radius (when compressed to the arc of a circle) -to form with the part A a complete cylindrical piston body. The free end of the band 4| is provided with a bevel l2, and the juxtaposed portion of the wall ii is formed with a complemental bevel 43.

In assembling the parts A and B the part B is fitted into the spaces provided in part A and the two abutting edges D and E are welded together so that the completed piston becomes a one piece body. When so welded the wall I forms a continuation of the wall II in the space C but the length of the wall I. is such as to leave a clearance 44 so that part B can be fully compressed when placed in an engine cylinder. When assembled the piston is heat treated so that the part B is given elasticity and set eccentric to the part A to resist any pressing tending to deform it to cylindrical shape.

In order that the united parts can be firlshed to a true cylindrical shape the band I is held by suitable means completely contacted into the .space 33 whereby the outer circumference can be machined and ground to the proper dimensions. When so ground'the band II is released and springs to its expanded position as shown in Figs. 9, 10, and 11.

It should be noted that a transverse rib ll is formed integral with the head ll onits inner face and extends diametrically thereof as a part of the two reinforcing ribs 35 and 31. Thus the head 3| and bosses 34 and II are tied together by a bridgelike construction well adapted to withstand the thrust of the piston as transmitted to the piston rod.

In the form of the invention shownin Figs. 12 to 17 inclusive a piston construction is illustrated for use where the two parts of the piston are of difi'erent metals and which cannot be welded together as described heretofore for other forms of the invention. In other words the form of the invention here illustrated makes it possible to provide a self expanding piston wherein such metals as aluminum for one part and cast iron for the other can be associated with the advantageous results heretofore specified.

Y In Fig. 12 the part C consists of a cylindrical head which is cast or otherwise formed integral with a cylindrical side wall 5| by means of two vertical ribs 52 and a reinforcing" bridge piece 53. In this connection it should be noted that the outer faces of the respective ribs 52 are spaced from the inner wall of the wall SI in order to provide a necessary clearance, the need for which will later be explained. As will be seen from Fig. 12 the head 50 is spaced vertically from the wall ii to form an annular space for the reception of the expansible. associated part D shown in Fig. 13. This part D consists of a band 54 having a width substantially that of the an- 'nular space provided in the part c and within then is brought to a position where the lu s it which it has a close snug fit against the respective abutting surfaces. divided as shown at -the opposed edges of which are bevelled as indicated so that when the band is clamped with these faces in {contact it are aimed with like lugs Iii formed integral with the wall II and provided with through openings II to receive the aforesaid pins 58. Also the head I is provided withtwo holes 62 properly positioned to aline with the holes 51 and through which the fastening and assembling pins 58 can be inserted to interlock the band 54 with the part C. The pins 58 are so dimensioned as to make a driving fit with the receiving holes and thereby to all intents and purposes have the effect of a complete integral joint between the band 54 and the head SI and wall II. As explained in connection with the other forms of the invention the band 54 is heat treated and set so that it has the required'elasticity ,and tends to deform itself into an eccentric shape to adequately grip the inner wall of a cylinder to prevent leakage past the piston. The lugs 60 as here shown are on opposite sides of one of the ribs 52 thus bringing the fixed part of the band at a rigid portion of the wall 5! and allowing the major portion of the aforesaid band M to be free tobe compressed or expanded relative to the head BI and wall ii in a manner well understood. As an integral part of the ribs 52 wrist pin bosses 83 are respectively provided in diametrically opposed relation on the inner face of the wall I. It will here be noted that the clearing 64 between the respective ribs 52 and the wall 5! allows for the unrestricted movement of the band it when in its proper aspiston head on one of said sections projecting laterally to close an end of the other section, and means for mounting a wrist pin in the assembled piston.

2. A self expanding piston consisting of two segmental sections of material secured together along two meeting edges, and the other meeting edges being complemental and spaced apart, a piston head on one of said sections projecting laterally to close an end of the other section, and means for mounting a wrist pin in the assembled piston.

3. A self expanding piston consisting of two segmental sections of material welded together along two meeting edges, and the other meeting edges having complemental offset portions, a piston head on one of said'sections projecting laterally to close an end of the other section while 7; allowing relative movement therebetween, and

This band 54' is split or means, for mounting a wrist pin in the assembled piston.

4. A self expanding piston consisting of two segmental sections of material secured together along two meeting edges, and the other meeting edges having complemental offset portions, each of'said sections comprising a pistonbody part and a skirt part, a piston head on one of said sections projecting laterally to close an end of the other section while allowing relative movement therebetween, each piston body part having circumferentially arranged grooves, and means for mounting a wrist pin in the assembled piston.

' 5. A self expanding piston consisting of two segmental sections of material secured tog ether along two meeting edges, and the other meeting edges having complemental offset portions, each of said sections comprising a pistonbody part having openings therethroug'h, and a skirt part, a piston head on one of said sections projecting laterally to close an end of the other section while allowing relative movement therebetween, each piston body part having circumferentially arranged grooves communicating with said openings, and means for mounting a wrist pin in the assembled piston.

6. A self expanding piston consisting of two segmental sections of material secured together along two meeting edges and the other meeting edges having complemental offset portions, each of said sections comprising a piston body part and a skirt part, a piston head on one of said sections projecting laterally to close an end of the other section while allowing relative movement therebetween, means to prevent oil leakage between the piston bodv parts, and means for mounting a wrist pin in the assembled piston.

'7. A self expanding piston consisting of two segmental sections of material secured together along two meeting edges and the other meeting edges having complemental offset portions, each of said sections comprising a piston body part and a skirt part, a piston head on one of said sections projecting laterally to close an end of the other section while allowing relative movement therebetween, means including a tongue to prevent oil leakage between the piston body parts, and means for mounting a wrist pin in the assembled piston.

8. A self expanding piston consisting of a cylindrical head, a side wall integral with and depending from said head, a circumferentially disposed extension on said wall forming with said head an arcuate space, a band arranged to fit within said arcuate space, said band having elasticity and being normally set to maintain a pressure on an encompassing-cylinder, bosses on said side wall, and means to attach one end of said band to said side wall.

9. A self expanding piston consisting of a cylindrical head, a side wall integral with and depending from said head, a circumferentially disposed extension on said wall forming with said head an arcuate space, a band arranged to fit within said arcuate space, said band having elasticity and being normally'set to maintain a pressure on an encompassing cylinder, means to at- Y tach one end of said band to said side wall, axially arranged bosses formed respectively on said wall and extension, and ribs respectively connecting said bosses to said head for reinforcing purposes.

disposed extension on said wall forming with 1" said head an arcuate space, a band arranged to fit within said arcuate space, said band having elasticity and being normally set to maintain a pressure on an encompassing cylinder, means to attach one end of said band to said side wall, axially arranged bosses formed respectively on said wall and extension, and ribs respectively connecting said bosses to said head for reinforcing purposes, one of said ribs bridging said arcuate space to form a clearance tor the movement of said band.

11. A self expanding piston consisting of a cylindrical head, a side wallintegral with and depending from said head, a circumferentially disposed extension on said wall forming with said head an arcuate space, a split band arranged to fit within said arcuate space, said band having elasticity and being normally set to maintain a pressure on an encompassing cylinder, and means to attach one end of said band to said side wall.

12. A self expanding piston consisting of a cylindrical head, a side wall integral with and elasticity and being normally set eccentric to the I contour 01' said head and wall, and means to rigidly fasten one end of said band to said side wall.

14. As a new article of manufacture a unitary piston having a head, and depending side wall, said wall having wrist pin bosses and a circumi'erentially disposed expansible eccentric portion located between said head and said bosses.

OSCAR C. PILL-AR. 

